Centrifugal machine for separating gold and mineral particles from metallurgical pulps



March 12, 1940. L s LACK 2,193,730

. CENTRIFUGAL MACHINE FOR SE ARATING GOLD AND MINERAL PARTICLES FROM METALLURGICAL PULPS Filed NQV. 25, 1938 Patented Mar. 12, 1940 UNITED STATES PATENT OFFICE Sydney Walter Lack, Waverley, near Sydney, New South Wales, Australia Application November 25, 1938, Serial No. 242,398 In Australia November 30, 1937 4 Claims.

This invention relates to a machine in which Centrifugal action is utilised to effect separation of free gold and other heavy mineral particles from metallurgical pulps, and in which gold 5 particles are amalgamated and the amalgam collected during the flow of free gold-containing pulp through the machine.

The nature of the invention will be understood from the following description of the accompanying drawing in which: 7 Fig. 1 is a central vertical sectional elevation through the machine;

Fig. 2 is a fragmentary detail view of part of a rotor jigging assembly; and

Fig. 3 is a detail sectional elevational view of one of the radial fingers with which the rotor is armed.

I is a frame rockable on trunnion blocks 56 and 51, H pulp supply pipe which depends into the hollow open-top dome l2 in the head of the rotor I3. The rotor is carried on a diaphragm 14 which is formed as a hub and is ported (15) to allow free flowing mineral pulp which is delivered into the dome l2 to flow downward into the sep- 25 arator chamber l6 of the rotor. The rotor I3 is open at the bottom, where it is provided with an inwardly dished rim I'I. Below this rim ll two concentric discharge hoppers I8 and I9 are fixed within the frame H), with their delivery spouts 2D and 21 disposed in different directions. 22 is a cylindrical partition disposed centrally under the rotor l3 and forming the inner wall of the spouted hopper 19. A clearance space 23 is provided between the top edge of the inner hopper l9 and the bottom edge of the rotor rim IT. The rotor I3 is fixed by a key 24 on a vertical spindle 25 and the upper end of the spindle is .carried in a bearing 26 in the top end of the 4 frame In. A driving pulley 21 is keyed on this spindle above the hearing.

A long tubularsleeve 36 is fitted over the part of the spindle 25 which is below the hub M. This sleeve runs in a bearing 3! in the lower part of the frame In, and a driving pulley 33 is keyed on it. It carries a collar 34 which is slung by trunnion pins 35 on the fork of a carrier lever 36 which is fulcrumed at 31 on a fixed bracket 33. The outer end of this lever is connected by a link 39 to a crank pin 40 on a transfer pulley 4| which runs on a fixed arbor 42. 43 is the main driving pulley; it runs on a fixed shaft 44. From it the spindle 25 is driven by a belt 45, and the transfer pulley 4| is also driven by a belt 46. A belt 41 communicates drive from the transfer pulley 4! to the pulley 33 on the bottom end of the sleeve 30. I

The driving arrangement which is described above is subject to rearrangement as in itself it does not form an element in the invention. For 5 instance, a vertical primary shaft may apply direct drive by belts to the pulleys 21 and 33 and 4!.

The concentric agitator barrel 50 is fixed to a flange 5! on the sleeve 30. It is armed peripherallywith fingers 52 which are carried on radial pins 53 so that they may slide and rotate freely thereon. When the barrel 50 is in rotation these floating fingers fly outwards as seen in Fig. 3 so that theythen approach but do not touch the interior surface of the vertical wall of the rotor l3. This interior surface of the rotor I3 is corrugated in horizontal rows as shown at 55, the cavities facing the floating fingers 52.

The speeds at which the rotor I3 and barrel 50 are rotated are adjusted to be not greatly different; the rotor and the barrel 50 rotate in the same direction. It is not essential that the barrel 50 be driven, as it will followthe rotor l3 at a more or less diminished speed. Either belt drive may be by cross belt, the fair lead pulleys, such as 58, being suitably angled. Vertical axial movement is applied to the drum through the rocking bar 36 and the apparatus as a whole is rocked on the trunnion blocks 56 and 51 by the transverse link rod 60 which is driven by the crank pin 40, the gudgeon end of which is centered on a fixed object 6|.

In operating on a pulp containing free gold, some mercury is introduced with the pulp through the feed pipe II at the beginning of the operation and as may be necessary during the operation. Drive is applied before the pulp is introduced and the flow of pulp is maintained at a regular rate. All the pulp runs through the machine except only the small proportion of the gold or mineral which is projected out of it by centrifugal action against the interior surface of the rotor, and is not washed down with the downflowing stream of pulpbutis retained in the corrugations on the rotor wall. This gold is 5 taken up by the mercury which also is caught and retained in the corrugations in the rotor wall. The floating fingers scrub the lagging material which tends to settle on the rotor wall, and keep the flow in a lively condition; they function also 5 to promote amalgamation of the gold with the mercury.

The peripheral speed of the rotor is adjusted so that the centrifugal effect operates to separate the free gold particles or the particles of heavy mineral which the pulp contains from the matrix ingredients and permits the non-separated material to fiow downward and to be ejected through the annular clearance space 23 into the tailings hopper [8.

The rocking movement applied to the machine during its rotation causes a washing efiect on the clownflowing pulp on the deposited and lagging material which is retained in the corrugations in the rotor wall; this rocking movement is, however, limited in range andis not suificient to throw separated particles off the rotor wall into the downfiowing current of pulp.

This washing action is made more efiective by the vertical jigging movement of the fingers 52 whilst the rotor and the agitator barrel are rotating at difierential peripheral velocities.

Then density of the pulp should be adjusted by experiment in each case to obtain optimum separation of the values from it. It is not practicable to foretell for any particular ore the best operating conditions; in the case of each orestufi' treated one or more trial runs are necessary to determine those conditions.

The discharging pulp tailings flood downward and are thrown outward centrifugally through the clearance 23 into the hopper I8 and thence go through the spout 29 to waste. At the conclusion of a run the pulp feed is stopped and then the machine is stopped; the amalgam and gold and heavy concentrates which have remained on the walls of the rotor are then dropped and are washed down into the values hopper I9 and pass thence outward through the spout 2!.

Mercury is not used except in the case of pulps which are treated for separation of free gold.

What is claimed is:

1. A mineral separating centrifugal machine comprising a hollow cylindrical vertically disposed rotor open at both ends, a vertical shaft carrying said rotor and having its bearings fixed in a trunnion mounted frame, a sleeve on said shaft, a co-axial agitator barrel carried on said sleeve within said rotor, a corrugated interior surface on the vertical wall of said rotor, means for applying rotation to said rotor and to said barrel, means for applying vertical jigging movement to said barrel, and means for applying rocking movement to the machine frame during the rotation of the barrel and the rotor and the vertical jigging movement of the barrel.

2. A mineral separating centrifugal machine according to claim 1 including agitator fingers projecting radially outward from the agitator barrel towards the rotor side wall.

3. A mineral separating centrifugal machine according to claim 1 including agitator fingers projecting radially outward from the agitator barrel towards the rotor side wall, said fingers comprising radial pins fixed in the wall of the agitator barrel, and cup-shaped members s1idable and rotatable on said pins.

4. A mineral separating centrifugal machine according to claim 1, including agitator fingers projecting radially outward from the agitator barrel toward the rotor side wall, concentric hop pars below the open bottom end of said rotor, and a feeder projecting into the open top domed and of said rotor.

SYDNEY WALTER LACK. 

